How do I scrub the sequencer playhead more than just 1 frame at a time
You can revert back to Blender 2.7X keymap in the Preferences



Edit: Sorry I didn't see the part about more than one frame at a time. My bad!

If you wish to stick with the current keymap though, you can add another keybind for that.

Head back over to the Preferences tab, go to the Keymap option, and scroll down until you find the Frames dropdown menu.

At the bottom of that menu, click Add New. That will add a none shortcut, so open it up, and enter screen.frame_offset into the text entry on the left side. A Delta property will then be added, and change that to however frames you want to jump by. Then, just assign what keys you want to bind it to.

Repeat the process for the shortcut you want to jump forward/backward. Negative delta for moving back, positive for forwards.